Identify the cranial nerves on this inferior-lateral view of a model brain showing blood supply
Trochlear Glossopharyngeal Vagus Accessory Olfactory tract Facial Vestibulochochlear Trigeminal Abducens
The Correct Answer and Explanation is :
- Trochlear (CN IV): The trochlear nerve is the smallest cranial nerve and is responsible for controlling the superior oblique muscle of the eye, which helps in eye movement. In an inferior-lateral view, it is often seen emerging near the midline of the brainstem, around the junction of the midbrain and pons.
- Glossopharyngeal (CN IX): This nerve is involved in taste, salivation, and monitoring blood pressure. It is located in the upper medulla, and you might find it extending laterally from the brainstem.
- Vagus (CN X): The vagus nerve has extensive functions, including regulating heart rate, digestion, and respiratory rate. It is situated laterally to the medulla and appears to descend further along the neck and chest.
- Accessory (CN XI): The accessory nerve controls certain shoulder and neck muscles. It typically emerges from the upper spinal cord and ascends through the foramen magnum to join the brainstem at the medulla level.
- Olfactory Tract (CN I): The olfactory nerve is the first cranial nerve and is responsible for the sense of smell. The olfactory tract is visible extending along the ventral surface of the brain, near the frontal lobes, though it doesn’t typically emerge from the brainstem.
- Facial (CN VII): The facial nerve is responsible for facial expressions, taste, and other functions. It exits laterally from the pons, near the junction with the medulla.
- Vestibulocochlear (CN VIII): This nerve deals with hearing and balance. It emerges near the junction of the pons and medulla, just lateral to the facial nerve.
- Trigeminal (CN V): The trigeminal nerve is the largest cranial nerve, responsible for sensation in the face and motor functions for chewing. It arises from the lateral part of the pons.
- Abducens (CN VI): The abducens nerve controls lateral eye movement. It emerges from the pons, near the midline, just below the facial nerve.
In the inferior-lateral view, these cranial nerves are arranged from the midline out toward the sides of the brainstem, and they can be seen exiting at various levels along the brainstem.